Homer, meet ‘Allen Gregory’

Jonah Hill’s latest role is a flat character — literally. But turning to cartoons is not that surprising for a guy who grew up idolizing “The Simpsons.”

A comic actor best known for his roles as chubby, not-quite-mature heroes in such films as “Superbad” and “Get Him to the Greek,” the 27-year-old Hill is a co-creator, writer, executive producer and star of “Allen Gregory,” which this fall joins Fox’s Sunday night animation lineup.

Hill and two writer friends developed the “Allen Gregory” concept after a feature they were planning failed to materialize He provides the voice of the title character, a precocious 7-year-old forced to adapt to life in a public school after his rich, flamboyantly gay father (French Stewart) suffers a reversal of fortune. On-screen, Allen Gregory is stylized like a 1960s magazine cartoon, with a huge mop of red hair, outsize tortoise-shell glasses and tiny, eraser-shaped feet.

“He’s a manipulator, and he can’t fathom doing something for someone else if it won’t serve him greatly,” Hill said of his character last spring after he and fellow cast members had just finished an hour-long table read in a conference room on the Fox lot (animated series record the vocal tracks first and then typically are animated and tweaked through a painstaking process that can take six months or longer). “He’s been told by everyone he’s the best because he’s been in this bubble. Now he’s going out into the real world, and he’s absolutely terrified.”

For someone about to take a high-profile project out into the real world, Hill seems remarkably relaxed; in fact, it’s sometimes hard to get him to answer a question without Hill making a joke. But the actor — who, by the way, has lost a considerable amount of weight since his “Superbad” days — knows he has a high standard to live up to.

“I’m a complete product of ‘The Simpsons,’” Hill said. “I wouldn’t be in entertainment without ‘The Simpsons.’ So I’d always wanted to create my own animated show one day.”

The big question now, though, is this: Is there another “Simpsons” out there?

A lot’s riding on the answer.

King of animation hill

Fox has a bullishness on prime-time cartoons that no other broadcast network has ever come close to matching. In fact, after “Allen Gregory” finishes its initial run of seven episodes in the winter will come an animated version of “Napoleon Dynamite,” the 2004 absurdist comedy about an oddball teenager in Idaho that developed a cult following. Both shows will air at 8:30 p.m. Sundays, in the plum slot between “The Simpsons” and “Family Guy,” creator Seth MacFarlane’s irreverent, manic, often nonsensical take on a nuclear family, which has become a sort of Avis to “The Simpsons’” Hertz. Also on the schedule are recent additions such as “The Cleveland Show” — a spin-off of “Family Guy” — and “Bob’s Burgers,” renewed for a second season after posting decent numbers last year. Other networks have made only scattered attempts to introduce animated series to prime time. NBC tried “God, the Devil and Bob” in 2000 and “Father of the Pride” in 2004; neither made it for a full season.

“Fox just has faith in the form,” said Mike Scully, a former “Simpsons” executive producer who’s now helping oversee “Napoleon Dynamite.” “They really believe in it; they know how to nurture and launch the shows.”

The network has been richly rewarded for its persistence. With “The Simpsons,” “Family Guy” and the now-defunct “King of the Hill,” the Sunday animation lineup became one of the most enduring and successful programming blocks in TV history, ultimately throwing off billions of dollars in revenue for the Fox studio. As the longest-running prime-time entertainment series in American history, longer than “Gunsmoke” or “Law & Order,” “The Simpsons” has probably done more than any other program to make the Fox network what it is today — more than even “American Idol,” which delivers several times as many viewers. (For the 2010-11 season, “The Simpsons” ranked only 68th in total viewers, averaging 7.3 million per week, but made the top 30 among adults ages 18 to 49, the demographic favored by most advertisers.)

When “The Simpsons” premiered in 1989, the Fox network was barely 3 years old and still struggling for traction. Within a few years, Homer Simpson — nuclear power-plant worker, bumbling patriarch and nightmare neighbor — had become the network’s most recognizable star as well as an enduring symbol of American culture. Early on, educators worried about the cultural impact of Bart, Homer’s smart-alecky, perpetually misbehaving son. “The Simpsons” has tagged Fox as a slightly naughty place, more subversive than the other guys and hence especially appealing to teenagers and twentysomething men. Those are the kind of hard-to-reach people advertisers will pay a premium to reach.

“The Simpsons” also changed the idea of animation on TV, which had almost completely disappeared in prime time since “The Flintstones” and “The Jetsons” in the 1960s. Created by cartoonist Matt Groening, the show was developed by James L. Brooks, who’d co-created TV’s landmark “Mary Tyler Moore Show” in the 1970s.

“Before ‘The Simpsons’ came on, animated shows used to be written by one or two people,” said Al Jean, the longtime showrunner of the Fox series. “The Simpsons” changed all that. It has a staff of 22 writers — larger than for many live-action prime-time shows — and always has two rewrite rooms running, where scripts are relentlessly tested and revised, Jean said. Over time, the show has subtly shifted some of the focus away from Bart and more on Homer, who seems to be losing IQ points as the years pass. But Jean says the writers have studiously attempted to stay true to its original subversive spirit, despite being viewed in some quarters as a “conservative institution.”

“Starting with ‘The Simpsons,’ [Fox] understood that the key to animated series succeeding in prime time is to write them with a writing staff like successful comedies in prime time have been written,” Jean said.

Not that the approach always works. Fox has seen its share of animated misfires, including “The Critic,” “The PJs” and, more recently, “Sit Down, Shut Up,” a 2009 high-school series that many critics complained went even beyond Fox’s standards in brazen offensiveness. Even “Family Guy,” now a major hit, was canceled twice before Fox executives realized its potential.

Then too, many viewers over age 40 simply have trouble relating to the genre.

“It’s a tough sell, because you’re really still trying to sell a children’s genre to grown-ups,” said Ray Richmond, a writer for Deadline.com and author of “The Simpsons: A Complete Guide to Our Favorite Family.” “It’s become far more an adult genre as time has gone on, but I think adults are skeptical at first until they’re convinced it’s playing at their level.”

As Gary Newman, who heads the Fox studio with Dana Walden, put it: “It’s hard to bring in an adult audience. We have to start with young people.”

All the young dudes

Specifically, they start with young males, who form the core audience of the Fox block. It’s no accident that one of the new cartoon entries comes from an actor well known for raunchy comedies aimed at college dudes, while the other is based on a cult movie that performed particularly well among young men.

Jared Hess, who co-directed the movie version of “Napoleon Dynamite,” says the TV adaptation will retain the offbeat flavor beloved by the film’s fans.

“We still have those awkward beats and pauses people found funny in the film,” he said. There’s also a rampage by ligers — the beasts that were a running joke in the movie — and an episode devoted to bed races, which actually take place in Preston, Idaho, the real-life town where the show is set.

Similarly, “Allen Gregory” relies for much of its humor on its own absurdist world — in contrast to “The Simpsons,” where the pop-cultural allusions spin at a dizzying pace.

Hill developed the TV show with Jarrad Paul and Andrew Mogel, a young writing team that’d been trying to get the actor to star in an offbeat romantic comedy they wrote called “Himmelfarb,” about a nerdy young man who follows the girl of his dreams to Nebraska. As it happened, Paul and Hill happened to live in the same apartment complex.

“We started waiting around Jonah’s door, wondering why he wasn’t doing our movie,” Mogel said.

Even now, an atmosphere of dorm-room silliness pervades behind the scenes at “Allen Gregory,” which presumably won’t hurt in connecting with that young-male target audience.

When asked whether the title character is based on a real person, Hill deadpanned: “Harrison Ford.” Paul kept the joke running, announcing that he was actually good friends with the “Star Wars” actor.

“It’s weird you use both names, if you’re actually friends,” Hill said. “It just seems if you were actually friends, you would’ve just said ‘Harrison.’”

“That’s what I said to him,” Paul replied, straight-faced.

Whether either “Allen Gregory” or “Napoleon Dynamite” connects with viewers remains to be seen. But Jean says the success of “The Simpsons” has ensured that the prime-time animated show will not disappear any time soon.

Some even see the cartoon form as a reflection of American mores — perhaps even more so than live-action shows.

“Probably, some of the best social commentary on television comes from the animated shows, along with Jon Stewart and Stephen Colbert,” Scully said. “Shows like ‘The Simpsons’ and ‘Family Guy’ really tap into the mood of the country.”

scott.collins@latimes.com